1. Field of Invention
The invention relates to a device for operation of a high pressure discharge lamp. The invention relates especially to such a device for operation which comprises a super-high pressure discharge lamp which is filled with at least 0.2 mg/mm3 of mercury and in which the pressure during operation reaches at least 200 atm, as well as to a feed device therefor.
2. Description of Related Art
Projector devices are generally of a type that uses a liquid crystal cell or a type that uses a DLP (digital light processor).
In the type using a liquid crystal cell, there are a one sheet type and a three sheet type. In each type, the following takes place:    The radiant light from the light source is separated into three colors (RGB; R=red, G=green, B=blue).    The light which contains the video information is transmitted and regulated by a liquid crystal cell;    Afterwards three colors which have been transmitted by the cell are combined and projected onto the screen.
In the type using the DLP there are also a one sheet type and a three sheet type. In the DLP one sheet type, the following takes place:    The radiant light from the light source is emitted via a rotary filter in which RGB areas are formed by division, onto a space modulation element (also called a light modulation device—specifically a D(igital) M(icro mirror) D(evice) element or the like should be understood here) or the like by time division,    Certain light is reflected from this DMD and emitted onto a screen.
Here, the term “DMD element” is defined as providing complete coverage with several hundred million small mirrors with the light projection being controlled by controlling the orientation of the individual small mirrors.
For the light source of the projector device, a high pressure discharge lamp with a high mercury vapor pressure is used. The reason for this is that, because the mercury vapor pressure is high, light in the visible wavelength range is emitted with high intensity.
Furthermore, formation of projections on the electrode tips during operation in such a discharge lamp is known. For example, in Japanese patent disclosure document 2002-175890 and corresponding U.S. Pat. No. 6,713,972, the presence of these projections is regarded as a disadvantage and a technology is presented in which the projections are caused to disappear. Specifically, a technology is disclosed in which the frequency of rated operation maintains a lower frequency (for example, 5 Hz) for at least 1 second, and in this way, the electrode surface is caused to melt so that the projections completely disappear.
Even if a high pressure discharge lamp has been used as the light source of a projector device by the above described technology, the arc spot did not become stable and so-called flicker formed to a great extent. This occurred especially in a discharge lamp with an amount of added mercury of at least 0.20 mg/mm3.